Go to PayPal and click the "Sign Up" link at the top of the page.
PayPal Personal accounts allow you to accept payments free of charge, except from credit cards. PayPal Premier and Business accounts charge fees but also allow you to accept credit card payments.
First, contact your buyer and decide together how you will refund the money. If you used PayPal, refund the amount by going to the PayPal “My Account” page, then the “History” tab. Find the payment and click Details, then click the “Issue refund” link. Enter the refund amount, then click Continue. After you’ve confirmed the details, click Process refund.